Pink Bacteria- Serratia marcescens

Have you often wondered, “What is that pink stuff around the drains in the sink or inside the toilet”?  Most often it is thought to be pink bacteria called Serratia marcescens.  Pink Bacteria is often found in water bowls of pets and even in swimming pools.Pink Bacteria


Pink bacteria or Serratia marcescens is an airborne bacterium that is found almost everywhere.  Serratia marcescens is a Gram negative rod shaped bacterium.  These pink bacteria are in dirt, and even places that are thought to be sterile.  S. marcescens is also found in subgingival biofilm of teeth and can cause staining of teeth.

The discovery of this bacterium was by a Venetian pharmacist in 1819 named Bartolomeo Bizio. The pink bacteria  S. marcescens was thought to be non –pathogenic until the 1950’s and was used as a simulant for biological warfare tests where S. marcescens was released into the air by bursting balloons over a populated area.   Within 2 days of this experiment 11 people developed serious urinary tract infections in a nearby hospital and cases of pneumonia increased as well. One death was reported.

In the 1960’s this pink bacteria was recognized as an opportunist pathogen in humans according to an article titled Serratia marcescens: historical perspective and clinical review in the New England Journal of Medicine in April 19 1979.

About 2 % of nosocomial infections are caused by S. marcescens. These infections usually affect the lower respiratory tract, urinary tract, surgical wounds, skin and soft tissues and can cause infections in the blood stream in adults. In children S.marcescens meningitis, wound infections and arthritis have been reported. 1

Prevention is the best way to avoid nosocomial infections such as these.  Surface disinfection with bleach based cleaner, rinsing and drying surface areas will make the environment less hospitable for growth.   Air purification and filtration can significantly reduce airborne pathogens such as these from becoming a problem.  S.marcescens is resistant to many antibiotics.  Hospitals, cancer treatment centers, and any place people with compromised immune systems are susceptible to a myriad of infections and illnesses.   Keeping their environment as clean as possible using air purification with photocatalytic oxidation and on surfaces using appropriate disinfectants can significantly reduce the spread of pink bacteria, S. marcescens and many other dangerous airborne pathogens like these that cause serious illnesses and even death.  7/11





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